A main target was Kirkuk, the largest city in the area claimed by several ethnic groups in a dispute with the central government in Baghdad. The conflict is one of several that threaten the stability of Iraq after the final pullout of U.S. military forces nearly a year ago.

After nightfall in Baghdad, a car bomb exploded near a Shiite mosque after evening prayers in Hurriya neighborhood, killing six worshippers and wounding 20 others, according to police and hospital officials.

In the north, a police officer said three bombs in parked cars exploded simultaneously in two Kurdish residential areas in the center of the city. One went off near a main Kurdish party headquarters. Five people, including a Kurdish security guard, were killed and 58 others wounded, he said.

A few minutes later, two bombs went off in a market in the Sunni-dominated town of Hawija west of Kirkuk, killing two civilians and wounding five others, he said.

Also, five Iraqi army soldiers were wounded when militants detonated bombs near their houses in the nearby town of Tuz Khortmato.